Date: Sun, 06 Feb 2011 16:20:54 -0600
From: Francis Ridge <nicap@insightbb.com>
Subject: Aug. 30, 1957; Chesapeake Bay, Nr. Norfolk, VA / Radar/Visual;
To: RADCAT


The following is Item 14 in the NARCAP report:

14. DATE: August 30, 1957                       TIME: night                       CLASS: R/V air radar/air visual

LOCATION:                                             SOURCES: Thayer (Condon 128)
Chesapeake Bay
Nr. Norfolk, Virginia                                  RADAR DURATION: unspecified

EVALUATIONS: Thayer - unknown

PRECIS: A Capital Airlines pilot with 17 years & 3,000,000 miles logged was flying a Viscount at 12,000' approaching Norfolk, Va., with a Northeast Airlines DC-6 "directly above" on the same heading at 20,000. The Viscount pilot saw a "brilliant" object which "flew fast and then abruptly halted 20 mi. in front of us at 60,000 ft. altitude." The Northeast pilot tried to acquire the object on radar: with the antenna at 0 degrees elevation nothing was detected, but with the antenna elevated to 15 degrees he acquired "an excellent blip right where I told him to look for the object." According to the Viscount pilot, the object "dissolved right in front of my eyes, and the crew above lost it from the scope at the same time. They said it just faded away." The entire incident lasted "several minutes".

NOTES: Thayer points out that if the DC-6 radar at 20,000' painted the target at 15 degrees elevation, range 20 miles, this would place the object at a little less than 50,000', not at the 60,000' estimated visually by the Viscount pilot. This might be thought a good match within the limits of observation and second-hand reportage (the DC-6 pilot did not apparently report his radar contact officially), and perhaps does not warrant Thayer's remark that the pilot's visual estimate was "in error". Further, the vertical coverage of the DC-6 radar would be at least several degrees and would paint a target with the antenna boresight aligned to a point somewhat below its real elevation (15 degrees quite possibly being the maximum antenna tilt limit), so it is not excluded that the match between visual-and radar-altitude indications was exact. Thayer's conclusion that the real visual elevation angle from the Viscount was 19 degrees, therefore, appears unwarranted, even if we accept the tacit assumption that radar and visual observations were of the same "object".

However, following Thayer's reasoning for the sake of argument, his analysis concludes that 19 degrees is too steep an angle for any temperature inversion to produce an optical mirage of a celestial body; and the above qualification of that reasoning increases the possible angle beyond 19 degrees, so further lessening the likelihood of mirage. Thayer also

NARCAP TR - 6                               Page 102
Date of Report:  12-02

dismisses partial inversion reflection of ground targets at optical or radar wavelengths, concluding that the incident must be considered an ''unknown".

Nevertheless, a question mark remains over the apparent absence of any visual sighting from the DC-6 of the "brilliant" light being watched from the Viscount. The DC-6 had to be "told where to look" in order to pick up the radar target; they did so, but apparently still saw nothing. Without an independent report from the crew of the DC-6 it is difficult to resolve this discrepancy. As it is, one must consider the possibility that the Viscount crew were watching something in local airspace which they mistook for a brilliant object at altitude, whilst the DC-6 radar indication was coincidental despite the reasonable match in reported position and time of disappearance. Individually, the visual report could be explained as an initial meteor plus (say) a nearby a/c turning its landing lights on and off, whilst the radar contact could have been system noise, interference, or a high-altitude ice-laden cloud which left radar coverage due to the plane's forward movement The DC-6 crew, meanwhile, would have been following Viscounf s directions and looking up, thus either not seeing a lit a/c below their altitude or assuming it was the Viscount (itself invisible directly below).

The above explanation may be less than probable, particularly given a visual duration of several minutes ("brilliance" of an a/c's forward-facing landing lights would imply a heading significantly away from that of the Viscount, and thus a fairly rapid relative motion), nevertheless it illustrates that the two sightings are insufficiently reported to evaluate with confidence. One possible explanation of the major part of the incident would be a high-altitude research balloon carrying an instrument payload. Such a balloon might reflect the sun brightly even in dark-sky conditions, and might appear suddenly from behind obscuring high clouds. When cut down it would rapidly collapse or shatter ("it dissolved right in front of my eyes") and its radar-reflective payload would fall away under gravity until its chute opened, thus possibly dropping out of the DC-6 radar pattern quite quickly if it were near the lower limit of coverage. However this explanation is quite speculative1: a) the time would require to be near dusk or dawn, but the time is not known; b) the a/c heading would have been roughly NS and the object was "in front", thus in the S sky and not ideally placed (i.e., not on the W horizon) to reflect the sun if sky conditions were "night" as reported; c) radar reportedly confirmed the object at less than 60,000', which is low for optimum chance of noctilucence and low for cut-down, which would normally take place at float altitudes above 100,000'; d) there is no explanation for the high­speed initial sighting without assuming a coincidental bright meteor; d) this construction requires a fortuitous distribution of cloud to explain why the illuminated balloon was seen for several minutes from the Viscount, but was at no time visible to the DC-6 crew flying 8000' above.

STATUS: Insufficient information